A fuel cell may be configured to have a layer where a large number of small pores are formed (hereinafter referred to as “porous layer”) placed between a catalyst layer and a gas diffusion layer. For example, an available method of forming the porous layer mixes particles including carbon black powder and polytetrafluoroethylene (PTFE) with a dispersed solution of PTFE to form a slurry and applies the slurry on a gas diffusion layer, as described in Patent Literature 1. In another example, as described in Patent Literature 2, another available method first mixes carbon particles with fine powder of PTFE using a blender and additionally adds a processing aid to obtain a mixture. The method subsequently extrudes and rolls the mixture to obtain a film and places the film between a catalyst layer and a gas diffusion layer. As described in Patent Literature 2, another available method adds a precipitating agent to a mixed solution of carbon particles and a dispersed solution of PTFE to coprecipitate carbon and PTFE, subsequently filtrates and dries the coprecipitate and subsequently adds a processing aid to obtain a mixture. The method subsequently extrudes and rolls the mixture to obtain a film and places the film between a catalyst layer and a gas diffusion layer.